Do I need to open the positioning when changing the yellow code to the green code?

No need. You don't need to open the positioning when changing the yellow code to the green code. When the yellow code turns to the green code, the mobile phone sends the location information to the management organization through traffic. Health codes are located according to cell phone signals, and operators will display each connected base station. Health codes are based on real data, which are declared online by citizens themselves, and personal QR codes are generated by background audit.